Allow more specific errno with remove

OLVASSEL.md

@@ -191,6 +191,7 @@ A `name` környezeti változó beállítása `len` hosszú `data` értékkel. Si
 
 | Funkció       | Leírás                                                                     |
 |---------------|----------------------------------------------------------------------------|
+| remove        | megszokott, de széles karakterű sztringet is elfogadhat                    |
 | fopen         | megszokott, de széles karakterű sztringet is elfogadhat, mode esetén is    |
 | fclose        | megszokott                                                                 |
 | fflush        | megszokott                                                                 |

README.md

@@ -187,6 +187,7 @@ Sets an environment variable by `name` with `data` of length `len`. On success r
 
 | Function      | Description                                                                |
 |---------------|----------------------------------------------------------------------------|
+| remove        | as usual, but might accept wide char strings                               |
 | fopen         | as usual, but might accept wide char strings, also for mode                |
 | fclose        | as usual                                                                   |
 | fflush        | as usual                                                                   |

uefi/stdio.c

@@ -155,6 +155,8 @@ int __remove (const char_t *__filename, int isdir)
     uintn_t fsiz = (uintn_t)sizeof(efi_file_info_t), i;
     /* little hack to support read and write mode for Delete() without create mode */
     FILE *f = fopen(__filename, CL("@"));
+    if(errno)
+        return 1;
     if(!f || f == stdin || f == stdout || f == stderr || (__ser && f == (FILE*)__ser)) {
         errno = EBADF;
         return 1;
@@ -204,6 +206,7 @@ FILE *fopen (const char_t *__filename, const char_t *__modes)
 #ifndef UEFI_NO_UTF8
     wchar_t wcname[BUFSIZ];
 #endif
+    errno = 0;
     if(!__filename || !*__filename || !__modes || !*__modes) {
         errno = EINVAL;
         return NULL;
@@ -269,7 +272,6 @@ FILE *fopen (const char_t *__filename, const char_t *__modes)
         errno = ENODEV;
         return NULL;
     }
-    errno = 0;
     ret = (FILE*)malloc(sizeof(FILE));
     if(!ret) return NULL;
     /* normally write means read,write,create. But for remove (internal '@' mode), we need read,write without create */